Biology of the Lung: A Multi-Disciplinary Approach has been the title and theme of this T32 since it began in 1975. For years 41-45, we propose to train 6 pre-doctoral PhD candidates, 8 MD postdoctoral fellows, and 3 PhD postdoctoral fellows per year in lung biology research. Our program will directly address the NHLBI- identified strategic training priorities by: 1) Providing multidisciplinary training and exposure of trainees o collaborative research. In this resubmission renewal application, we will provide lung biology training in 5 scientific foci that are special strengths at BU: Regenerative Medicine and Developmental Biology; Genomics and Bioinformatics; Infection and Immunity; Biomedical Engineering; and Clinical Research Sciences. This training will be provided by an exceptional faculty, including 49 mentors from 4 schools, clustered into 5 Scientific Focus Groups. 2) Developing new investigators with the necessary competencies and breadth of expertise needed for the future of biomedical research. Our training will directly address the NHLBI strategic areas of regenerative and reparative medicine, omics and computational biology, bioengineering, immunology and infectious diseases, and epidemiologic and population research including comparative effectiveness and outcomes research. 3) Ensuring that trainees receive adequate mentorship, and that mentorship is taught and evaluated. Our training program is mature and will continue to follow very well- established, formal, careful, and caring career guidance and mentorship plans, with tiered structures that ensure oversight by senior leaders and dedicated professional guidance experts. 4) Recruiting and retaining such investigators in the scientific workforce and ensuring adequate representation of the nation's diversity in that workforce. The BU environment is ideal for recruiting and advancing trainees from diverse backgrounds, as evidenced by its 140 year history of training minority students and our successful T32 track record. Programs designed by our T32 for recruitment and retention of scientists from under-represented groups have been so successful that they have become adopted school-wide. 5) Providing a continued flow of qualified physician-scientists able to translate findings freely between the basic and clinical spheres. The keystone principle of our training is bi-directional translation of ideas between basic and clinical spheres. That is why we train MD fellows together with PhD students and fellows in a unified program. Our T32 structure will ensure that postdoctoral MD physician-scientists train side-by-side with PhD pre-doctoral students and postdoctoral fellows, learning from each other as well as their mentors, in Scientific Focus Groups integrating basic science with clinical science as applied to lung disease. The proposed training will address the key strategic interests of the NHLBI. Our trainees will benefit from superb research training in a highly integrated educational and career guidance model. Our current program plan represents the very best we have offered in over 40 years of producing lung researchers.